Fast secondary cell recovery for ultra-reliable low-latency communication

ABSTRACT

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment may provide, to a first cell, a beam failure indication associated with a beam of a secondary cell. The beam failure indication may be provided via a dedicated physical uplink control channel (PUCCH) resource. The user equipment may provide, based at least in part on providing the beam failure indication, a beam index report to a second cell. The beam index report may be provided to cause recovery of the secondary cell to be triggered. The beam index report may include information that identifies a preferred beam associated with the recovery of the secondary cell. Numerous other aspects are provided.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No.62/742,880, filed on Oct. 8, 2018, entitled “FAST SECONDARY CELLRECOVERY FOR ULTRA-RELIABLE LOW-LATENCY COMMUNICATION,” which is herebyexpressly incorporated by reference herein.

FIELD OF THE DISCLOSURE

Aspects of the present disclosure generally relate to wirelesscommunication, and to techniques and apparatuses for fast secondary cellrecovery for ultra-reliable low-latency communication (URLLC).

BACKGROUND

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources (e.g., bandwidth,transmit power, and/or the like). Examples of such multiple-accesstechnologies include code division multiple access (CDMA) systems, timedivision multiple access (TDMA) systems, frequency-division multipleaccess (FDMA) systems, orthogonal frequency-division multiple access(OFDMA) systems, single-carrier frequency-division multiple access(SC-FDMA) systems, time division synchronous code division multipleaccess (TD-SCDMA) systems, and Long Term Evolution (LTE).LTE/LTE-Advanced is a set of enhancements to the Universal MobileTelecommunications System (UMTS) mobile standard promulgated by theThird Generation Partnership Project (3GPP).

A wireless communication network may include a number of base stations(BSs) that can support communication for a number of user equipment(UEs). A user equipment (UE) may communicate with a base station (BS)via the downlink and uplink. The downlink (or forward link) refers tothe communication link from the BS to the UE, and the uplink (or reverselink) refers to the communication link from the UE to the BS. As will bedescribed in more detail herein, a BS may be referred to as a Node B, agNB, an access point (AP), a radio head, a transmit receive point (TRP),a New Radio (NR) BS, a 5G Node B, and/or the like.

The above multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent user equipment to communicate on a municipal, national,regional, and even global level. New Radio (NR), which may also bereferred to as 5G, is a set of enhancements to the LTE mobile standardpromulgated by the Third Generation Partnership Project (3GPP). NR isdesigned to better support mobile broadband Internet access by improvingspectral efficiency, lowering costs, improving services, making use ofnew spectrum, and better integrating with other open standards usingorthogonal frequency division multiplexing (OFDM) with a cyclic prefix(CP) (CP-OFDM) on the downlink (DL), using CP-OFDM and/or SC-FDM (e.g.,also known as discrete Fourier transform spread OFDM (DFT-s-OFDM)) onthe uplink (UL), as well as supporting beamforming, multiple-inputmultiple-output (MIMO) antenna technology, and carrier aggregation.However, as the demand for mobile broadband access continues toincrease, there exists a need for further improvements in LTE and NRtechnologies. Preferably, these improvements should be applicable toother multiple access technologies and the telecommunication standardsthat employ these technologies.

SUMMARY

In some aspects, a method of wireless communication, performed by a userequipment, may include providing, to a first cell, a beam failureindication associated with a beam of a secondary cell, wherein the beamfailure indication is provided via a dedicated physical uplink controlchannel (PUCCH) resource; and providing, based at least in part onproviding the beam failure indication, a beam index report to a secondcell, wherein the beam index report is to cause recovery of thesecondary cell to be triggered, and wherein the beam index reportincludes information that identifies a preferred beam associated withthe recovery of the secondary cell.

In some aspects, a user equipment for wireless communication may includememory and one or more processors operatively coupled to the memory. Thememory and the one or more processors may be configured to provide, to afirst cell, a beam failure indication associated with a beam of asecondary cell, wherein the beam failure indication is provided via adedicated PUCCH resource; and provide, based at least in part onproviding the beam failure indication, a beam index report to a secondcell, wherein the beam index report is to cause recovery of thesecondary cell to be triggered, and wherein the beam index reportincludes information that identifies a preferred beam associated withthe recovery of the secondary cell.

In some aspects, a non-transitory computer-readable medium may store oneor more instructions for wireless communication. The one or moreinstructions, when executed by one or more processors of a userequipment, may cause the one or more processors to provide, to a firstcell, a beam failure indication associated with a beam of a secondarycell, wherein the beam failure indication is provided via a dedicatedPUCCH resource; and provide, based at least in part on providing thebeam failure indication, a beam index report to a second cell, whereinthe beam index report is to cause recovery of the secondary cell to betriggered, and wherein the beam index report includes information thatidentifies a preferred beam associated with the recovery of thesecondary cell.

In some aspects, an apparatus for wireless communication may includemeans for providing, to a first cell, a beam failure indicationassociated with a beam of a secondary cell, wherein the beam failureindication is provided via a dedicated PUCCH resource; and means forproviding, based at least in part on providing the beam failureindication, a beam index report to a second cell, wherein the beam indexreport is to cause recovery of the secondary cell to be triggered, andwherein the beam index report includes information that identifies apreferred beam associated with the recovery of the secondary cell.

In some aspects, the aspects described herein may apply to non-URLLCtraffic (e.g., regular traffic). In other words, the aspects describedherein are not limited to fast recovery of a secondary cell associatedwith URLLC traffic, and may be applied in association with fast recoveryof a secondary cell for another type of traffic.

Aspects generally include a method, apparatus, system, computer programproduct, non-transitory computer-readable medium, user equipment, basestation, wireless communication device, and processing system assubstantially described herein with reference to and as illustrated bythe accompanying drawings and specification.

The foregoing has outlined rather broadly the features and technicaladvantages of examples according to the disclosure in order that thedetailed description that follows may be better understood. Additionalfeatures and advantages will be described hereinafter. The conceptionand specific examples disclosed may be readily utilized as a basis formodifying or designing other structures for carrying out the samepurposes of the present disclosure. Such equivalent constructions do notdepart from the scope of the appended claims. Characteristics of theconcepts disclosed herein, both their organization and method ofoperation, together with associated advantages will be better understoodfrom the following description when considered in connection with theaccompanying figures. Each of the figures is provided for the purpose ofillustration and description, and not as a definition of the limits ofthe claims.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the above-recited features of the present disclosure can beunderstood in detail, a more particular description, briefly summarizedabove, may be had by reference to aspects, some of which are illustratedin the appended drawings. It is to be noted, however, that the appendeddrawings illustrate only certain typical aspects of this disclosure andare therefore not to be considered limiting of its scope, for thedescription may admit to other equally effective aspects. The samereference numbers in different drawings may identify the same or similarelements.

FIG. 1 is a block diagram conceptually illustrating an example of awireless communication network, in accordance with various aspects ofthe present disclosure.

FIG. 2 is a block diagram conceptually illustrating an example of a basestation in communication with a user equipment (UE) in a wirelesscommunication network, in accordance with various aspects of the presentdisclosure.

FIG. 3A is a block diagram conceptually illustrating an example of aframe structure in a wireless communication network, in accordance withvarious aspects of the present disclosure.

FIG. 3B is a block diagram conceptually illustrating an examplesynchronization communication hierarchy in a wireless communicationnetwork, in accordance with various aspects of the present disclosure.

FIG. 4 is a block diagram conceptually illustrating an example slotformat with a normal cyclic prefix, in accordance with various aspectsof the present disclosure.

FIG. 5 is a diagram illustrating an example of a downlink (DL)-centricslot, in accordance with various aspects of the present disclosure.

FIG. 6 is a diagram illustrating an example of an uplink (UL)-centricslot, in accordance with various aspects of the present disclosure.

FIGS. 7A-7E are diagrams illustrating examples of fast secondary cellrecovery for URLLC, in accordance with various aspects of the presentdisclosure.

FIG. 8 is a diagram illustrating an example process performed, forexample, by a user equipment, in accordance with various aspects of thepresent disclosure.

DETAILED DESCRIPTION

Various aspects of the disclosure are described more fully hereinafterwith reference to the accompanying drawings. This disclosure may,however, be embodied in many different forms and should not be construedas limited to any specific structure or function presented throughoutthis disclosure. Rather, these aspects are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art. Based on theteachings herein one skilled in the art should appreciate that the scopeof the disclosure is intended to cover any aspect of the disclosuredisclosed herein, whether implemented independently of or combined withany other aspect of the disclosure. For example, an apparatus may beimplemented or a method may be practiced using any number of the aspectsset forth herein. In addition, the scope of the disclosure is intendedto cover such an apparatus or method which is practiced using otherstructure, functionality, or structure and functionality in addition toor other than the various aspects of the disclosure set forth herein. Itshould be understood that any aspect of the disclosure disclosed hereinmay be embodied by one or more elements of a claim.

Several aspects of telecommunication systems will now be presented withreference to various apparatuses and techniques. These apparatuses andtechniques will be described in the following detailed description andillustrated in the accompanying drawings by various blocks, modules,components, circuits, steps, processes, algorithms, and/or the like(collectively referred to as “elements”). These elements may beimplemented using hardware, software, or combinations thereof. Whethersuch elements are implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem.

It should be noted that while aspects may be described herein usingterminology commonly associated with 3G and/or 4G wireless technologies,aspects of the present disclosure can be applied in othergeneration-based communication systems, such as 5G and later, includingNR technologies.

FIG. 1 is a diagram illustrating a network 100 in which aspects of thepresent disclosure may be practiced. The network 100 may be an LTEnetwork or some other wireless network, such as a 5G or NR network.Wireless network 100 may include a number of BSs 110 (shown as BS 110 a,BS 110 b, BS 110 c, and BS 110 d) and other network entities. A BS is anentity that communicates with user equipment (UEs) and may also bereferred to as a base station, a NR BS, a Node B, a gNB, a 5G node B(NB), an access point, a transmit receive point (TRP), and/or the like.Each BS may provide communication coverage for a particular geographicarea. In 3GPP, the term “cell” can refer to a coverage area of a BSand/or a BS subsystem serving this coverage area, depending on thecontext in which the term is used.

A BS may provide communication coverage for a macro cell, a pico cell, afemto cell, and/or another type of cell. A macro cell may cover arelatively large geographic area (e.g., several kilometers in radius)and may allow unrestricted access by UEs with service subscription. Apico cell may cover a relatively small geographic area and may allowunrestricted access by UEs with service subscription. A femto cell maycover a relatively small geographic area (e.g., a home) and may allowrestricted access by UEs having association with the femto cell (e.g.,UEs in a closed subscriber group (CSG)). ABS for a macro cell may bereferred to as a macro BS. ABS for a pico cell may be referred to as apico BS. A BS for a femto cell may be referred to as a femto BS or ahome BS. In the example shown in FIG. 1, a BS 110 a may be a macro BSfor a macro cell 102 a, a BS 110 b may be a pico BS for a pico cell 102b, and a BS 110 c may be a femto BS for a femto cell 102 c. A BS maysupport one or multiple (e.g., three) cells. The terms “eNB”, “basestation”, “NR BS”, “gNB”, “TRP”, “AP”, “node B”, “5G NB”, and “cell” maybe used interchangeably herein.

In some aspects, a cell may not necessarily be stationary, and thegeographic area of the cell may move according to the location of amobile BS. In some aspects, the BSs may be interconnected to one anotherand/or to one or more other BSs or network nodes (not shown) in theaccess network 100 through various types of backhaul interfaces such asa direct physical connection, a virtual network, and/or the like usingany suitable transport network.

Wireless network 100 may also include relay stations. A relay station isan entity that can receive a transmission of data from an upstreamstation (e.g., a BS or a UE) and send a transmission of the data to adownstream station (e.g., a UE or a BS). A relay station may also be aUE that can relay transmissions for other UEs. In the example shown inFIG. 1, a relay station 110 d may communicate with macro BS 110 a and aUE 120 d in order to facilitate communication between BS 110 a and UE120 d. A relay station may also be referred to as a relay BS, a relaybase station, a relay, and/or the like.

Wireless network 100 may be a heterogeneous network that includes BSs ofdifferent types, e.g., macro BSs, pico BSs, femto BSs, relay BSs, and/orthe like. These different types of BSs may have different transmit powerlevels, different coverage areas, and different impacts on interferencein wireless network 100. For example, macro BSs may have a high transmitpower level (e.g., 5 to 40 Watts) whereas pico BSs, femto BSs, and relayBSs may have lower transmit power levels (e.g., 0.1 to 2 Watts).

A network controller 130 may couple to a set of BSs and may providecoordination and control for these BSs. Network controller 130 maycommunicate with the BSs via a backhaul. The BSs may also communicatewith one another, e.g., directly or indirectly via a wireless orwireline backhaul.

UEs 120 (e.g., 120 a, 120 b, 120 c) may be dispersed throughout wirelessnetwork 100, and each UE may be stationary or mobile. A UE may also bereferred to as an access terminal, a terminal, a mobile station, asubscriber unit, a station, and/or the like. A UE may be a cellularphone (e.g., a smart phone), a personal digital assistant (PDA), awireless modem, a wireless communication device, a handheld device, alaptop computer, a cordless phone, a wireless local loop (WLL) station,a tablet, a camera, a gaming device, a netbook, a smartbook, anultrabook, a medical device or equipment, biometric sensors/devices,wearable devices (smart watches, smart clothing, smart glasses, smartwrist bands, smart jewelry (e.g., smart ring, smart bracelet)), anentertainment device (e.g., a music or video device, or a satelliteradio), a vehicular component or sensor, smart meters/sensors,industrial manufacturing equipment, a global positioning system device,or any other suitable device that is configured to communicate via awireless or wired medium.

Some UEs may be considered machine-type communication (MTC) or evolvedor enhanced machine-type communication (eMTC) UEs. MTC and eMTC UEsinclude, for example, robots, drones, remote devices, sensors, meters,monitors, location tags, and/or the like, that may communicate with abase station, another device (e.g., remote device), or some otherentity. A wireless node may provide, for example, connectivity for or toa network (e.g., a wide area network such as Internet or a cellularnetwork) via a wired or wireless communication link. Some UEs may beconsidered Internet-of-Things (IoT) devices, and/or may be implementedas NB-IoT (narrowband internet of things) devices. Some UEs may beconsidered a Customer Premises Equipment (CPE). UE 120 may be includedinside a housing that houses components of UE 120, such as processorcomponents, memory components, and/or the like.

In general, any number of wireless networks may be deployed in a givengeographic area. Each wireless network may support a particular RAT andmay operate on one or more frequencies. A RAT may also be referred to asa radio technology, an air interface, and/or the like. A frequency mayalso be referred to as a carrier, a frequency channel, and/or the like.Each frequency may support a single RAT in a given geographic area inorder to avoid interference between wireless networks of different RATs.In some cases, NR or 5G RAT networks may be deployed.

In some aspects, two or more UEs 120 (e.g., shown as UE 120 a and UE 120e) may communicate directly using one or more sidelink channels (e.g.,without using a base station 110 as an intermediary to communicate withone another). For example, the UEs 120 may communicate usingpeer-to-peer (P2P) communications, device-to-device (D2D)communications, a vehicle-to-everything (V2X) protocol (e.g., which mayinclude a vehicle-to-vehicle (V2V) protocol, a vehicle-to-infrastructure(V2I) protocol, and/or the like), a mesh network, and/or the like. Inthis case, the UE 120 may perform scheduling operations, resourceselection operations, and/or other operations described elsewhere hereinas being performed by the base station 110.

As indicated above, FIG. 1 is provided merely as an example. Otherexamples may differ from what is described with regard to FIG. 1.

FIG. 2 shows a block diagram of a design 200 of base station 110 and UE120, which may be one of the base stations and one of the UEs in FIG. 1.Base station 110 may be equipped with T antennas 234 a through 234 t,and UE 120 may be equipped with R antennas 252 a through 252 r, where ingeneral T≥1 and R≥1.

At base station 110, a transmit processor 220 may receive data from adata source 212 for one or more UEs, select one or more modulation andcoding schemes (MCS) for each UE based at least in part on channelquality indicators (CQIs) received from the UE, process (e.g., encodeand modulate) the data for each UE based at least in part on the MCS(s)selected for the UE, and provide data symbols for all UEs. Transmitprocessor 220 may also process system information (e.g., for semi-staticresource partitioning information (SRPI) and/or the like) and controlinformation (e.g., CQI requests, grants, upper layer signaling, and/orthe like) and provide overhead symbols and control symbols. Transmitprocessor 220 may also generate reference symbols for reference signals(e.g., the cell-specific reference signal (CRS)) and synchronizationsignals (e.g., the primary synchronization signal (PSS) and secondarysynchronization signal (SSS)). A transmit (TX) multiple-inputmultiple-output (MIMO) processor 230 may perform spatial processing(e.g., precoding) on the data symbols, the control symbols, the overheadsymbols, and/or the reference symbols, if applicable, and may provide Toutput symbol streams to T modulators (MODs) 232 a through 232 t. Eachmodulator 232 may process a respective output symbol stream (e.g., forOFDM and/or the like) to obtain an output sample stream. Each modulator232 may further process (e.g., convert to analog, amplify, filter, andupconvert) the output sample stream to obtain a downlink signal. Tdownlink signals from modulators 232 a through 232 t may be transmittedvia T antennas 234 a through 234 t, respectively. According to variousaspects described in more detail below, the synchronization signals canbe generated with location encoding to convey additional information.

At UE 120, antennas 252 a through 252 r may receive the downlink signalsfrom base station 110 and/or other base stations and may providereceived signals to demodulators (DEMODs) 254 a through 254 r,respectively. Each demodulator 254 may condition (e.g., filter, amplify,downconvert, and digitize) a received signal to obtain input samples.Each demodulator 254 may further process the input samples (e.g., forOFDM and/or the like) to obtain received symbols. A MIMO detector 256may obtain received symbols from all R demodulators 254 a through 254 r,perform MIMO detection on the received symbols if applicable, andprovide detected symbols. A receive processor 258 may process (e.g.,demodulate and decode) the detected symbols, provide decoded data for UE120 to a data sink 260, and provide decoded control information andsystem information to a controller/processor 280. A channel processormay determine reference signal received power (RSRP), received signalstrength indicator (RSSI), reference signal received quality (RSRQ),channel quality indicator (CQI), and/or the like. In some aspects, oneor more components of UE 120 may be included in a housing.

On the uplink, at UE 120, a transmit processor 264 may receive andprocess data from a data source 262 and control information (e.g., forreports comprising RSRP, RSSI, RSRQ, CQI, and/or the like) fromcontroller/processor 280. Transmit processor 264 may also generatereference symbols for one or more reference signals. The symbols fromtransmit processor 264 may be precoded by a TX MIMO processor 266 ifapplicable, further processed by modulators 254 a through 254 r (e.g.,for DFT-s-OFDM, CP-OFDM, and/or the like), and transmitted to basestation 110. At base station 110, the uplink signals from UE 120 andother UEs may be received by antennas 234, processed by demodulators232, detected by a MIMO detector 236 if applicable, and furtherprocessed by a receive processor 238 to obtain decoded data and controlinformation sent by UE 120. Receive processor 238 may provide thedecoded data to a data sink 239 and the decoded control information tocontroller/processor 240. Base station 110 may include communicationunit 244 and communicate to network controller 130 via communicationunit 244. Network controller 130 may include communication unit 294,controller/processor 290, and memory 292.

Controller/processor 240 of base station 110, controller/processor 280of UE 120, and/or any other component(s) of FIG. 2 may perform one ormore techniques associated with fast secondary cell recovery for URLLC,as described in more detail elsewhere herein. For example,controller/processor 240 of base station 110, controller/processor 280of UE 120, and/or any other component(s) of FIG. 2 may perform or directoperations of, for example, process 800 of FIG. 8 and/or other processesas described herein. Memories 242 and 282 may store data and programcodes for base station 110 and UE 120, respectively. A scheduler 246 mayschedule UEs for data transmission on the downlink and/or uplink.

In some aspects, a UE (e.g., UE 120) may include means for providing, toa first cell, a beam failure indication associated with a beam of asecondary cell, wherein the beam failure indication is provided via adedicated PUCCH resource; means for providing, based at least in part onproviding the beam failure indication, a beam index report to a secondcell, wherein the beam index report is to cause recovery of thesecondary cell to be triggered, and wherein the beam index reportincludes information that identifies a preferred beam associated withthe recovery of the secondary cell; and/or the like. In some aspects,such means may include one or more components of UE 120 described inconnection with FIG. 2.

As indicated above, FIG. 2 is provided merely as an example. Otherexamples may differ from what is described with regard to FIG. 2.

FIG. 3A shows an example frame structure 300 for FDD in atelecommunications system (e.g., NR). The transmission timeline for eachof the downlink and uplink may be partitioned into units of radio frames(sometimes referred to as frames). Each radio frame may have apredetermined duration (e.g., 10 milliseconds (ms)) and may bepartitioned into a set of Z (Z≥1) subframes (e.g., with indices of 0through Z−1). Each subframe may have a predetermined duration (e.g., 1ms) and may include a set of slots (e.g., 2^(m) slots per subframe areshown in FIG. 3A, where m is a numerology used for a transmission, suchas 0, 1, 2, 3, 4, and/or the like). Each slot may include a set of Lsymbol periods. For example, each slot may include fourteen symbolperiods (e.g., as shown in FIG. 3A), seven symbol periods, or anothernumber of symbol periods. In a case where the subframe includes twoslots (e.g., when m=1), the subframe may include 2L symbol periods,where the 2L symbol periods in each subframe may be assigned indices of0 through 2L−1. In some aspects, a scheduling unit for the FDD mayframe-based, subframe-based, slot-based, symbol-based, and/or the like.

While some techniques are described herein in connection with frames,subframes, slots, and/or the like, these techniques may equally apply toother types of wireless communication structures, which may be referredto using terms other than “frame,” “subframe,” “slot,” and/or the likein 5G NR. In some aspects, a wireless communication structure may referto a periodic time-bounded communication unit defined by a wirelesscommunication standard and/or protocol. Additionally, or alternatively,different configurations of wireless communication structures than thoseshown in FIG. 3A may be used.

In certain telecommunications (e.g., NR), a base station may transmitsynchronization signals. For example, a base station may transmit aprimary synchronization signal (PSS), a secondary synchronization signal(SSS), and/or the like, on the downlink for each cell supported by thebase station. The PSS and SSS may be used by UEs for cell search andacquisition. For example, the PSS may be used by UEs to determine symboltiming, and the SSS may be used by UEs to determine a physical cellidentifier, associated with the base station, and frame timing. The basestation may also transmit a physical broadcast channel (PBCH). The PBCHmay carry some system information, such as system information thatsupports initial access by UEs.

In some aspects, the base station may transmit the PSS, the SSS, and/orthe PBCH in accordance with a synchronization communication hierarchy(e.g., a synchronization signal (SS) hierarchy) including multiplesynchronization communications (e.g., SS blocks), as described below inconnection with FIG. 3B.

FIG. 3B is a block diagram conceptually illustrating an example SShierarchy, which is an example of a synchronization communicationhierarchy. As shown in FIG. 3B, the SS hierarchy may include an SS burstset, which may include a plurality of SS bursts (identified as SS burst0 through SS burst B−1, where B is a maximum number of repetitions ofthe SS burst that may be transmitted by the base station). As furthershown, each SS burst may include one or more SS blocks (identified as SSblock 0 through SS block (b_(max_SS)−1), where b_(max_SS)−1 is a maximumnumber of SS blocks that can be carried by an SS burst). In someaspects, different SS blocks may be beam-formed differently. An SS burstset may be periodically transmitted by a wireless node, such as every Xmilliseconds, as shown in FIG. 3B. In some aspects, an SS burst set mayhave a fixed or dynamic length, shown as Y milliseconds in FIG. 3B.

The SS burst set shown in FIG. 3B is an example of a synchronizationcommunication set, and other synchronization communication sets may beused in connection with the techniques described herein. Furthermore,the SS block shown in FIG. 3B is an example of a synchronizationcommunication, and other synchronization communications may be used inconnection with the techniques described herein.

In some aspects, an SS block includes resources that carry the PSS, theSSS, the PBCH, and/or other synchronization signals (e.g., a tertiarysynchronization signal (TSS)) and/or synchronization channels. In someaspects, multiple SS blocks are included in an SS burst, and the PSS,the SSS, and/or the PBCH may be the same across each SS block of the SSburst. In some aspects, a single SS block may be included in an SSburst. In some aspects, the SS block may be at least four symbol periodsin length, where each symbol carries one or more of the PSS (e.g.,occupying one symbol), the SSS (e.g., occupying one symbol), and/or thePBCH (e.g., occupying two symbols).

In some aspects, the symbols of an SS block are consecutive, as shown inFIG. 3B. In some aspects, the symbols of an SS block arenon-consecutive. Similarly, in some aspects, one or more SS blocks ofthe SS burst may be transmitted in consecutive radio resources (e.g.,consecutive symbol periods) during one or more slots. Additionally, oralternatively, one or more SS blocks of the SS burst may be transmittedin non-consecutive radio resources.

In some aspects, the SS bursts may have a burst period, whereby the SSblocks of the SS burst are transmitted by the base station according tothe burst period. In other words, the SS blocks may be repeated duringeach SS burst. In some aspects, the SS burst set may have a burst setperiodicity, whereby the SS bursts of the SS burst set are transmittedby the base station according to the fixed burst set periodicity. Inother words, the SS bursts may be repeated during each SS burst set.

The base station may transmit system information, such as systeminformation blocks (SIBs) on a physical downlink shared channel (PDSCH)in certain slots. The base station may transmit control information/dataon a physical downlink control channel (PDCCH) in C symbol periods of aslot, where B may be configurable for each slot. The base station maytransmit traffic data and/or other data on the PDSCH in the remainingsymbol periods of each slot.

As indicated above, FIGS. 3A and 3B are provided as examples. Otherexamples may differ from what is described with regard to FIGS. 3A and3B.

FIG. 4 shows an example slot format 410 with a normal cyclic prefix. Theavailable time frequency resources may be partitioned into resourceblocks. Each resource block may cover a set of subcarriers (e.g., 12subcarriers) in one slot and may include a number of resource elements.Each resource element may cover one subcarrier in one symbol period(e.g., in time) and may be used to send one modulation symbol, which maybe a real or complex value.

An interlace structure may be used for each of the downlink and uplinkfor FDD in certain telecommunications systems (e.g., NR). For example, Qinterlaces with indices of 0 through Q−1 may be defined, where Q may beequal to 4, 6, 8, 10, or some other value. Each interlace may includeslots that are spaced apart by Q frames. In particular, interlace q mayinclude slots q, q+Q, q+2Q, etc., where qϵ{0, . . . , Q−1}.

A UE may be located within the coverage of multiple BSs. One of theseBSs may be selected to serve the UE. The serving BS may be selectedbased at least in part on various criteria such as received signalstrength, received signal quality, path loss, and/or the like. Receivedsignal quality may be quantified by a signal-to-noise-and-interferenceratio (SNIR), or a reference signal received quality (RSRQ), or someother metric. The UE may operate in a dominant interference scenario inwhich the UE may observe high interference from one or more interferingBSs.

While aspects of the examples described herein may be associated with NRor 5G technologies, aspects of the present disclosure may be applicablewith other wireless communication systems. New Radio (NR) may refer toradios configured to operate according to a new air interface (e.g.,other than Orthogonal Frequency Divisional Multiple Access (OFDMA)-basedair interfaces) or fixed transport layer (e.g., other than InternetProtocol (IP)). In aspects, NR may utilize OFDM with a CP (hereinreferred to as cyclic prefix OFDM or CP-OFDM) and/or SC-FDM on theuplink, may utilize CP-OFDM on the downlink and include support forhalf-duplex operation using TDD. In aspects, NR may, for example,utilize OFDM with a CP (herein referred to as CP-OFDM) and/or discreteFourier transform spread orthogonal frequency-division multiplexing(DFT-s-OFDM) on the uplink, may utilize CP-OFDM on the downlink andinclude support for half-duplex operation using TDD. NR may includeEnhanced Mobile Broadband (eMBB) service targeting wide bandwidth (e.g.,80 megahertz (MHz) and beyond), millimeter wave (mmW) targeting highcarrier frequency (e.g., 60 gigahertz (GHz)), massive MTC (mMTC)targeting non-backward compatible MTC techniques, and/or missioncritical targeting ultra reliable low latency communications (URLLC)service.

In some aspects, a single component carrier bandwidth of 100 MHz may besupported. NR resource blocks may span 12 sub-carriers with asub-carrier bandwidth of 60 or 120 kilohertz (kHz) over a 0.1millisecond (ms) duration. Each radio frame may include 40 slots and mayhave a length of 10 ms. Consequently, each slot may have a length of0.25 ms. Each slot may indicate a link direction (e.g., DL or UL) fordata transmission and the link direction for each slot may bedynamically switched. Each slot may include DL/UL data as well as DL/ULcontrol data.

Beamforming may be supported and beam direction may be dynamicallyconfigured. MIMO transmissions with precoding may also be supported.MIMO configurations in the DL may support up to 8 transmit antennas withmulti-layer DL transmissions up to 8 streams and up to 2 streams per UE.Multi-layer transmissions with up to 2 streams per UE may be supported.Aggregation of multiple cells may be supported with up to 8 servingcells. Alternatively, NR may support a different air interface, otherthan an OFDM-based interface. NR networks may include entities such ascentral units or distributed units.

As indicated above, FIG. 4 is provided as an example. Other examples maydiffer from what is described with regard to FIG. 4.

FIG. 5 is a diagram 500 showing an example of a DL-centric slot orwireless communication structure. The DL-centric slot may include acontrol portion 502. The control portion 502 may exist in the initial orbeginning portion of the DL-centric slot. The control portion 502 mayinclude various scheduling information and/or control informationcorresponding to various portions of the DL-centric slot. In someconfigurations, the control portion 502 may be a physical DL controlchannel (PDCCH), as indicated in FIG. 5. In some aspects, the controlportion 502 may include legacy PDCCH information, shortened PDCCH(sPDCCH) information), a control format indicator (CFI) value (e.g.,carried on a physical control format indicator channel (PCFICH)), one ormore grants (e.g., downlink grants, uplink grants, and/or the like),and/or the like.

The DL-centric slot may also include a DL data portion 504. The DL dataportion 504 may sometimes be referred to as the payload of theDL-centric slot. The DL data portion 504 may include the communicationresources utilized to communicate DL data from the scheduling entity(e.g., UE or BS) to the subordinate entity (e.g., UE). In someconfigurations, the DL data portion 504 may be a physical DL sharedchannel (PDSCH).

The DL-centric slot may also include an UL short burst portion 506. TheUL short burst portion 506 may sometimes be referred to as an UL burst,an UL burst portion, a common UL burst, a short burst, an UL shortburst, a common UL short burst, a common UL short burst portion, and/orvarious other suitable terms. In some aspects, the UL short burstportion 506 may include one or more reference signals. Additionally, oralternatively, the UL short burst portion 506 may include feedbackinformation corresponding to various other portions of the DL-centricslot. For example, the UL short burst portion 506 may include feedbackinformation corresponding to the control portion 502 and/or the dataportion 504. Non-limiting examples of information that may be includedin the UL short burst portion 506 include an ACK signal (e.g., a PUCCHACK, a PUSCH ACK, an immediate ACK), a NACK signal (e.g., a PUCCH NACK,a PUSCH NACK, an immediate NACK), a scheduling request (SR), a bufferstatus report (BSR), a HARQ indicator, a channel state indication (CSI),a channel quality indicator (CQI), a sounding reference signal (SRS), ademodulation reference signal (DMRS), PUSCH data, and/or various othersuitable types of information. The UL short burst portion 506 mayinclude additional or alternative information, such as informationpertaining to random access channel (RACH) procedures, schedulingrequests, and various other suitable types of information.

As illustrated in FIG. 5, the end of the DL data portion 504 may beseparated in time from the beginning of the UL short burst portion 506.This time separation may sometimes be referred to as a gap, a guardperiod, a guard interval, and/or various other suitable terms. Thisseparation provides time for the switch-over from DL communication(e.g., reception operation by the subordinate entity (e.g., UE)) to ULcommunication (e.g., transmission by the subordinate entity (e.g., UE)).The foregoing is merely one example of a DL-centric wirelesscommunication structure, and alternative structures having similarfeatures may exist without necessarily deviating from the aspectsdescribed herein.

As indicated above, FIG. 5 is provided merely as an example. Otherexamples may differ from what is described with regard to FIG. 5.

FIG. 6 is a diagram 600 showing an example of an UL-centric slot orwireless communication structure. The UL-centric slot may include acontrol portion 602. The control portion 602 may exist in the initial orbeginning portion of the UL-centric slot. The control portion 602 inFIG. 6 may be similar to the control portion 502 described above withreference to FIG. 5. The UL-centric slot may also include an UL longburst portion 604. The UL long burst portion 604 may sometimes bereferred to as the payload of the UL-centric slot. The UL portion mayrefer to the communication resources utilized to communicate UL datafrom the subordinate entity (e.g., UE) to the scheduling entity (e.g.,UE or BS). In some configurations, the control portion 602 may be aphysical DL control channel (PDCCH).

As illustrated in FIG. 6, the end of the control portion 602 may beseparated in time from the beginning of the UL long burst portion 604.This time separation may sometimes be referred to as a gap, guardperiod, guard interval, and/or various other suitable terms. Thisseparation provides time for the switch-over from DL communication(e.g., reception operation by the scheduling entity) to UL communication(e.g., transmission by the scheduling entity).

The UL-centric slot may also include an UL short burst portion 606. TheUL short burst portion 606 in FIG. 6 may be similar to the UL shortburst portion 506 described above with reference to FIG. 5, and mayinclude any of the information described above in connection with FIG.5. The foregoing is merely one example of an UL-centric wirelesscommunication structure, and alternative structures having similarfeatures may exist without necessarily deviating from the aspectsdescribed herein.

In some circumstances, two or more subordinate entities (e.g., UEs) maycommunicate with each other using sidelink signals. Real-worldapplications of such sidelink communications may include public safety,proximity services, UE-to-network relaying, vehicle-to-vehicle (V2V)communications, Internet of Everything (IoE) communications, IoTcommunications, mission-critical mesh, and/or various other suitableapplications. Generally, a sidelink signal may refer to a signalcommunicated from one subordinate entity (e.g., UE1) to anothersubordinate entity (e.g., UE2) without relaying that communicationthrough the scheduling entity (e.g., UE or BS), even though thescheduling entity may be utilized for scheduling and/or controlpurposes. In some aspects, the sidelink signals may be communicatedusing a licensed spectrum (unlike wireless local area networks, whichtypically use an unlicensed spectrum).

In one example, a wireless communication structure, such as a frame, mayinclude both UL-centric slots and DL-centric slots. In this example, theratio of UL-centric slots to DL-centric slots in a frame may bedynamically adjusted based at least in part on the amount of UL data andthe amount of DL data that are transmitted. For example, if there ismore UL data, then the ratio of UL-centric slots to DL-centric slots maybe increased. Conversely, if there is more DL data, then the ratio ofUL-centric slots to DL-centric slots may be decreased.

As indicated above, FIG. 6 is provided merely as an example. Otherexamples may differ from what is described with regard to FIG. 6.

Upon detecting a beam failure of a beam associated with a secondarycell, beam recovery should be performed as quickly as possible (e.g.,such that the UE can continue to receive and/or transmit communicationsvia the secondary cell). Fast recovery of the secondary cell isparticularly useful when the secondary cell is used for traffic withstrict latency and/or reliability requirements, such as ultra-reliablelow-latency (URLLC) traffic. In a case where a first cell (e.g., aprimary cell) remains operational despite the beam failure associatedwith the secondary cell (e.g., when a beam associated with the firstcell and the beam associated with the secondary cell are at differentfrequencies), recovery of the secondary cell can be enabled via thefirst cell.

Some aspects described herein provide techniques and apparatuses forfast recovery of a secondary cell. In some aspects, the fast recoverymay be used when the secondary cell is used for traffic with strictlatency and/or reliability requirements (e.g., URLLC traffic). In someaspects, the fast recovery of the secondary cell improves operation of auser equipment by reducing a latency of communications that whenrecovering from a beam failure of a beam associated with a secondarycell. In some aspects, the fast recovery of the secondary cell conservespower of the user equipment that may otherwise be wasted whencommunications fail due to the beam failure of the beam associated withthe secondary cell.

FIGS. 7A-7E are diagrams illustrating examples of fast secondary cellrecovery for URLLC, in accordance with various aspects of the presentdisclosure. In FIGS. 7A-7E, a beam of a secondary cell (e.g., associatedwith a base station (BS) 110) is to be used for transmissions of URLLCtraffic between a UE (e.g., UE 120) and the secondary cell.

FIG. 7A is a diagram of an example 700 of fast secondary cell recoveryfor URLLC. As shown in FIG. 7A, and by reference number 702, a UE (e.g.,UE 120) may detect a beam failure associated with the secondary cell.For example, the UE may detect, based at least in part on a referencesignal associated with the secondary cell (SCell RS), a beam failureassociated with a beam of the secondary cell. In some aspects, the UEmay detect the beam failure when one or more measurements of thereference signal, associated with the secondary cell, satisfy athreshold. In some aspects, the threshold may be expressed in terms ofan INSYC or OUT OF SYNC BLER, targeted to match a hypothetical PDCCHperformance transmitted with the beam. As another example, the UE maydetect the beam failure when a particular number of signal strengthmeasurements of the reference signal (e.g., one or more measurements, avalue that is a function of two or more measurements, and/or the like)are less than a threshold signal strength (e.g., during a particulartime window).

As shown by reference number 704, the UE may provide, to a first cell(e.g., a primary cell associated with base station 110) a beam failureindication associated with the beam of the secondary cell. In someaspects, the beam failure indication acts as an indication that recoveryof the secondary cell is needed.

In some aspects, the UE may provide the beam failure indication in adedicated physical uplink control channel (PUCCH) resource (sometimesreferred to as a dedicated scheduling request (SR)). In some aspects,the dedicated PUCCH uplink resource may be a low-overhead resource, suchas a single bit in the PUCCH that is reserved for providing a beamfailure indication. In some aspects, information that identifies thededicated PUCCH resource may be configured on the UE (e.g., based atleast in part on signaling provided by the base station).

In some aspects, the UE may provide a SCell index associated with thesecondary cell. For example, the UE may report the SCell index,associated with the secondary cell, in a medium access control (MAC)control element. In some aspects, the UE may provide the SCell indexafter the UE provides the beam failure indication in the dedicated PUCCHresource (e.g., in a separate communication).

In some aspects, as shown by reference number 706, the UE may receive abeam index report request from a second cell after the UE provides thebeam failure indication. For example, the first cell may receive thebeam failure indication, and the second cell may send, to the UE, arequest for a beam index report (e.g., via a PDCCH). In some aspects,the first and second cells may be the same cell. In some aspects, thefirst and second cells may be different cells. For example, in someaspect the first cell may be a primary cell, and the second cell may bea cell in a same cell group as the primary cell. In some aspects, thesecond cell may be a cell that supports uplink transmissions. In someaspects, the secondary cell may be used for downlink transmissions only.

In some aspects, the beam index report request may be carried in anormal uplink grant scrambled with cell radio network temporaryidentifier (C-RNTI) or a modulation and coding scheme cell radio networktemporary identifier (MCS-C-RNTI).

As shown by reference number 708, the UE may provide a beam index report(sometimes referred to as a layer 1 (L1) report) based at least in parton the beam index report request received from the second cell. Forexample, the UE may receive the beam index report request, generate abeam index report, and provide the beam index report to the second cell.

In some aspects, the beam index report may include information thatidentifies a preferred beam associated with the recovery of thesecondary cell. For example, the beam index report may includeinformation (e.g., an 8 bit sequence) that identifies a beam indexcorresponding to a preferred beam (e.g., a beam that the UE has selectedas a suitable beam for recovery of the secondary cell based at least inpart on detecting one or more SSBs associated with the beam). In someaspects, the beam index report may be carried in a medium access controlcontrol element (MAC-CE) dedicated to secondary cell beam failurerecovery.

In some aspects, confirmation of reception of the beam index report maybe a normal uplink grant scheduling a transmission for a same hybridautomatic repeat request (HARD) process as a physical uplink sharedchannel (PUSCH) carrying the beam index report.

In some aspects, the UE may provide the beam index report in order tocause recovery of the secondary cell to be triggered (e.g., based atleast in part on the beam index report), as described in further detailbelow.

In some aspects, based at least in part on the beam index reportprovided by the UE, recovery of the secondary cell may be triggered. Insome aspects, as shown by reference number 710, the recovery of thesecondary cell may be performed based at least in part on a dynamic(i.e., on-demand) random access channel (RACH) procedure associated withbeam pairing between the secondary cell and the UE. For example, thesecond cell may activate a RACH procedure on the secondary cell for thebeam index associated with the preferred beam (e.g., as identified inthe beam index report). In some other aspects, a sounding referencesignal (SRS) transmission from the UE can be triggered by the basestation in order to enable beam pairing. In some examples, the SRS canbe triggered to be quasi co-located (QCL) with the reported beam in thebeam index report associated with the secondary cell.

As shown by reference number 712, the UE and the secondary cell may thenengage in beam pairing based at least in part on the RACH procedurebeing activated on the secondary cell. For example, the UE may transmit,using a first transmit beam, an initial RACH message (e.g., MSG1). Here,if the UE receives a responsive RACH message (e.g., MSG2), then the RACHprocedure may proceed until beam pairing is complete and the secondarycell is recovered, as indicated in FIG. 7A.

Alternatively, if the initial RACH message fails (e.g., if the UE doesnot receive MSG2 within a threshold amount of time), then the UE mayretransmit, using a second transmit beam (e.g., a differently configuredtransmit beam, such as a beam with a comparatively higher power) theinitial RACH message and await a responsive RACH message. This processmay be repeated until the UE receives a responsive RACH message (afterwhich beam pairing can be completed and the secondary cell isrecovered). In some aspects, the RACH-based approach is advantageous inorder to enable fast secondary cell recovery without beam correspondencebetween the downlink and uplink beams (e.g., since the UE can adjustand/or reconfigure the transmit beam each time the UE retransmits theinitial RACH message).

FIG. 7B is a diagram of an example 720 of fast secondary cell recoveryfor URLLC. As shown by reference number 722, a UE (e.g., UE 120) maydetect a beam failure associated with the secondary cell. In someaspects, the UE may detect the beam failure in a manner similar to thatdescribed above in association with reference number 702 of FIG. 7A.

As shown by reference number 724, the UE may provide, to a first cell(e.g., a primary cell associated with base station (BS) 110) a beamfailure indication associated with the beam of the secondary cell. Insome aspects, the UE may provide the beam failure indication in a mannersimilar to that described above in association with reference number 704of FIG. 7A.

As shown by reference number 728, the UE may automatically provide thebeam report index to the first cell, in some aspects. For example, theUE may be configured with a reporting delay that identifies an amount oftime (e.g., a number of slots) after providing the beam failureindication that the UE is to wait before automatically providing thebeam index report. Here, the UE may, after an amount of time equal tothe reporting delay has lapsed, automatically (e.g., without a requestfrom the second cell) provide the beam index report to the second cell.In some aspects, the reporting delay may be configured on the UE (e.g.,based at least in part on signaling provided by the first cell or thesecond cell). In some aspects, the reporting delay provides schedulingflexibility at the base station (e.g., such that the base station hastime to schedule uplink transmissions around resources in which thesecond cell is to receive the beam index report). In some aspects,providing the beam index report based at least in part on the reportingdelay reduces latency associated with recovery of the secondary cell,which may be useful when the secondary cell is used for URLLC traffic.

In some aspects, based at least in part on the beam index reportautomatically provided by the UE, recovery of the secondary cell may betriggered. In some aspects, as shown by reference number 730, therecovery of the secondary cell may be performed based at least in parton a dynamic RACH procedure associated with beam pairing between thesecondary cell and the UE. For example, the second cell may activate aRACH procedure on the secondary cell for the beam index associated withthe preferred beam (e.g., as identified in the beam index report). Thedynamic RACH procedure may be similar to that described above inassociation with reference number 710 of FIG. 7A.

As shown by reference number 732, the UE and the secondary cell may thenengage in beam pairing based at least in part on the RACH procedurebeing activated on the secondary cell. The beam pairing may be conductedin a similar manner to that described above in association withreference number 712 of FIG. 7A.

FIG. 7C is a diagram of an example 740 of fast secondary cell recoveryfor URLLC. As shown by reference number 742, a UE (e.g., UE 120) maydetect a beam failure associated with the secondary cell. In someaspects, the UE may detect the beam failure in a manner similar to thatdescribed above in association with reference number 702 of FIG. 7A.

As shown by reference number 744, the UE may provide, to a first cell(e.g., a primary cell associated with base station (BS) 110) a beamfailure indication associated with the beam of the secondary cell. Insome aspects, the UE may provide the beam failure indication in a mannersimilar to that described above in association with reference number 704of FIG. 7A.

As shown by reference number 748, the UE may automatically provide thebeam report index to the first cell, in some aspects. In some aspects,the UE may automatically provide the beam failure indication in a mannersimilar to that described above in association with reference number 728of FIG. 7A.

In some aspects, based at least in part on the beam index reportautomatically provided by the UE, recovery of the secondary cell may betriggered. In some aspects, as shown by reference number 754, therecovery of the secondary cell may be performed based at least in parton a downlink control information (DCI) or media access control (MAC)control element beam update associated with the secondary cell. Forexample, upon receiving the beam index report, the second cell mayupdate a DCI/MAC control element (MAC-CE), associated with the secondarycell, such that the UE can begin receiving communications from thesecondary cell using the preferred beam, as identified by the beam indexreport.

FIG. 7D is a diagram of an example 760 of fast secondary cell recoveryfor URLLC. As shown by reference number 762, a UE (e.g., UE 120) maydetect a beam failure associated with the secondary cell. In someaspects, the UE may detect the beam failure in a manner similar to thatdescribed above in association with reference number 702 of FIG. 7A.

As shown by reference number 764/768, the UE may provide, to a firstcell (e.g., a primary cell associated with base station (BS) 110) a beamfailure indication associated with the beam of the secondary cell, alongwith a beam index report. In other words, in some aspects, the UE may beconfigured to provide the beam failure indication and the beam indexreport in a single communication. In some aspects, the singlecommunication that includes the beam failure indication and the beamindex report may include information similar to that described above inassociation with reference numbers 704 and 708, respectively, of FIG.7A. In some aspects, providing the beam failure indication and the beamindex report in the same communication reduces latency associated withrecovery of the secondary cell, which may be useful when the secondarycell is used for URLLC traffic.

In some aspects, based at least in part on the beam index report beingprovided by the UE along with the beam failure indication, recovery ofthe secondary cell may be triggered. In some aspects, as shown byreference number 770, the recovery of the secondary cell may beperformed based at least in part on a dynamic RACH procedure associatedwith beam pairing between the secondary cell and the UE. For example,the second cell may activate a RACH procedure on the secondary cell forthe beam index associated with the preferred beam (e.g., as identifiedin the beam index report). The dynamic RACH procedure may be similar tothat described above in association with reference number 710 of FIG.7A.

As shown by reference number 772, the UE and the secondary cell may thenengage in beam pairing based at least in part on the RACH procedurebeing activated on the secondary cell. The beam pairing may be conductedin a similar manner to that described above in association withreference number 712 of FIG. 7A.

FIG. 7E is a diagram of an example 780 of fast secondary cell recoveryfor URLLC. As shown by reference number 782, a UE (e.g., UE 120) maydetect a beam failure associated with the secondary cell. In someaspects, the UE may detect the beam failure in a manner similar to thatdescribed above in association with reference number 702 of FIG. 7A.

As shown by reference number 784/788, the UE may provide, to a firstcell (e.g., a primary cell associated with base station (BS) 110) a beamfailure indication associated with the beam of the secondary cell in asingle communication to the first cell (e.g., in a manner similar to thedescribed above in association with reference number 764/768 of FIG.7D).

In some aspects, based at least in part on the beam index reportprovided by the UE along with the beam failure indication, recovery ofthe secondary cell may be triggered. In some aspects, as shown byreference number 794, the recovery of the secondary cell may beperformed based at least in part on a DCI or MAC control element beamupdate associated with the secondary cell (e.g., in a manner similar tothe described above in association with reference number 754 of FIG.7C).

In some aspects, a manner in which information associated with a beamfailure (e.g., a beam failure indication, a beam index report, and/orthe like) is provided by the UE may be determined based at least in parton the beam being associated with URLLC traffic. For example, the UE maybe configured such that information associated with a beam failure of abeam used for URLLC traffic is to be provided in a particular mannerdescribed above (e.g., automatically, based at least in part on areporting delay, and/or the like). In this way, beam failure reportingcan be triggered differently for beams associated with URLLC traffic(e.g., as compared to beams used for regular traffic, beams used fornon-URLLC traffic, and/or the like). In some aspects, an association ofa given beam with URLLC traffic may be indicated via a URLLC controlresource set, beam monitoring via a particular radio network temporaryidentifier (RNTI), via a URLLC search space identifier, via a radioresource control (RRC)/MAC control element/DCI configuration of certainbeams as URLLC, and/or the like.

As indicated above, FIGS. 7A-7E are provided as examples. Other examplesmay differ from what is described with respect to FIGS. 7A-7E.

FIG. 8 is a diagram illustrating an example process 800 performed, forexample, by a UE, in accordance with various aspects of the presentdisclosure. Example process 800 is an example where a wirelesscommunication device (e.g., base station 110, UE 120) performs fastsecondary cell recovery for URLLC.

As shown in FIG. 8, in some aspects, process 800 may include providing,to a first cell, a beam failure indication associated with a beam of asecondary cell, wherein the beam failure indication is provided via adedicated PUCCH resource (block 810). For example, the UE (e.g., usingantenna 252, TX MIMO processor 266, transmit processor 264,controller/processor 250, and/or the like) may provide, to a first cell(e.g., a primary cell associated with base station 110), a beam failureindication associated with a beam of a secondary cell (e.g., associatedwith base station 110) wherein the beam failure indication is providedvia a dedicated PUCCH resource, as described above. In some aspects, thebeam may be associated with URLLC traffic.

As shown in FIG. 8, in some aspects, process 800 may include providing,based at least in part on providing the beam failure indication, a beamindex report to a second cell, wherein the beam index report is to causerecovery of the secondary cell to be triggered, and wherein the beamindex report includes information that identifies a preferred beamassociated with the recovery of the secondary cell (block 820). Forexample, the UE (e.g., using antenna 252, TX MIMO processor 266,transmit processor 264, controller/processor 250, and/or the like) mayprovide, based at least in part on providing the beam failureindication, a beam index report to a second cell (e.g., the primary cellassociated with base station 110, another cell associated with basestation 110, and/or the like), wherein the beam index report is to causerecovery of the secondary cell to be triggered, and wherein the beamindex report includes information that identifies a preferred beamassociated with the recovery of the secondary cell, as described above.

Process 800 may include additional aspects, such as any single aspect orany combination of aspects described below and/or in connection with oneor more other processes described elsewhere herein.

In a first aspect, the beam is associated with ultra-reliablelow-latency traffic.

In a second aspect, alone or in combination with the first aspect, thefirst cell and the second cell are a same cell.

In a third aspect, alone or in combination with one or more of the firstand second aspects, the first cell is a primary cell, the primary cellis in a same cell group as the secondary cell.

In a fourth aspect, alone or in combination with one or more of thefirst through third aspects, the secondary cell is used for downlinktransmissions only.

In a fifth aspect, alone or in combination with one or more of the firstthrough fourth aspects, the second cell is a cell that supports uplinktransmissions.

In a sixth aspect, alone or in combination with one or more of the firstthrough fifth aspects, the beam index report is provided based at leastin part on a beam index report request that is received from the secondcell, wherein the beam index report request is received after the beamfailure indication is provided.

In a seventh aspect, alone or in combination with one or more of thefirst through sixth aspects, the beam index report request is a normaluplink grant scrambled with cell radio network temporary identifier(C-RNTI) or a modulation and coding scheme cell radio network temporaryidentifier (MCS-C-RNTI).

In an eighth aspect, alone or in combination with one or more of thefirst through seventh aspects, the beam index report is carried in amedium access control control element (MAC-CE) dedicated to secondarycell beam failure recovery.

In a ninth aspect, alone or in combination with one or more of the firstthrough eighth aspects, confirmation of reception of the beam indexreport is a normal uplink grant scheduling a transmission for a samehybrid automatic repeat request (HARD) process as a physical uplinkshared channel (PUSCH) carrying the beam index report.

In a tenth aspect, alone or in combination with one or more of the firstthrough ninth aspects, the beam index report is automatically providedbased at least in part on a reporting delay, wherein the reporting delayidentifies an amount of time after providing the beam failureindication, that the UE is to wait before automatically providing thebeam index report.

In an eleventh aspect, alone or in combination with one or more of thefirst through tenth aspects, the beam index report is provided in a samecommunication as the beam failure indication.

In a twelfth aspect, alone or in combination with one or more of thefirst through eleventh aspects, the recovery of the secondary cell isbased at least in part on a dynamic random access channel (RACH)procedure associated with beam pairing between the secondary cell andthe UE.

In a thirteenth aspect, alone or in combination with one or more of thefirst through twelfth aspects, the recovery of the secondary cell isbased at least in part on a downlink control information (DCI) beamupdate associated with the secondary cell.

In a fourteenth aspect, alone or in combination with one or more of thefirst through thirteenth aspects, the recovery of the secondary cell isbased at least in part on a media access control (MAC) control elementbeam update associated with the secondary cell.

In a fifteenth aspect, alone or in combination with one or more of thefirst through fourteenth aspects, a manner in which the beam failureindication is provided is determined based at least in part on the beambeing associated with ultra-reliable low-latency traffic.

In a sixteenth aspect, alone or in combination with one or more of thefirst through fifteenth aspects, process 800 includes providing asecondary cell index associated with the secondary cell in the beamindex report.

Although FIG. 8 shows example blocks of process 800, in some aspects,process 800 may include additional blocks, fewer blocks, differentblocks, or differently arranged blocks than those depicted in FIG. 8.Additionally, or alternatively, two or more of the blocks of process 800may be performed in parallel.

The foregoing disclosure provides illustration and description, but isnot intended to be exhaustive or to limit the aspects to the preciseform disclosed. Modifications and variations may be made in light of theabove disclosure or may be acquired from practice of the aspects.

As used herein, the term component is intended to be broadly construedas hardware, firmware, or a combination of hardware and software. Asused herein, a processor is implemented in hardware, firmware, or acombination of hardware and software.

Some aspects are described herein in connection with thresholds. As usedherein, satisfying a threshold may refer to a value being greater thanthe threshold, greater than or equal to the threshold, less than thethreshold, less than or equal to the threshold, equal to the threshold,not equal to the threshold, and/or the like.

It will be apparent that systems and/or methods, described herein, maybe implemented in different forms of hardware, firmware, or acombination of hardware and software. The actual specialized controlhardware or software code used to implement these systems and/or methodsis not limiting of the aspects. Thus, the operation and behavior of thesystems and/or methods were described herein without reference tospecific software code—it being understood that software and hardwarecan be designed to implement the systems and/or methods based, at leastin part, on the description herein.

Even though particular combinations of features are recited in theclaims and/or disclosed in the specification, these combinations are notintended to limit the disclosure of various aspects. In fact, many ofthese features may be combined in ways not specifically recited in theclaims and/or disclosed in the specification. Although each dependentclaim listed below may directly depend on only one claim, the disclosureof various aspects includes each dependent claim in combination withevery other claim in the claim set. A phrase referring to “at least oneof” a list of items refers to any combination of those items, includingsingle members. As an example, “at least one of: a, b, or c” is intendedto cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combinationwith multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c,a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering ofa, b, and c).

No element, act, or instruction used herein should be construed ascritical or essential unless explicitly described as such. Also, as usedherein, the articles “a” and “an” are intended to include one or moreitems, and may be used interchangeably with “one or more.” Furthermore,as used herein, the terms “set” and “group” are intended to include oneor more items (e.g., related items, unrelated items, a combination ofrelated and unrelated items, and/or the like), and may be usedinterchangeably with “one or more.” Where only one item is intended, theterm “only one” or similar language is used. Also, as used herein, theterms “has,” “have,” “having,” and/or the like are intended to beopen-ended terms. Further, the phrase “based on” is intended to mean“based, at least in part, on” unless explicitly stated otherwise.

1. A method of wireless communication performed by a user equipment(UE), comprising: providing, to a first cell, a beam failure indicationassociated with a beam of a secondary cell, wherein the beam failureindication is provided via a dedicated physical uplink control channel(PUCCH) resource; and providing, based at least in part on providing thebeam failure indication, a beam index report to a second cell, whereinthe beam index report is to cause recovery of the secondary cell to betriggered, and wherein the beam index report includes information thatidentifies a preferred beam associated with the recovery of thesecondary cell.
 2. The method of claim 1, wherein the beam is associatedwith ultra-reliable low-latency traffic.
 3. The method of claim 1,wherein the first cell and the second cell are a same cell.
 4. Themethod of claim 1, wherein the first cell is a primary cell, wherein theprimary cell is in a same cell group as the secondary cell.
 5. Themethod of claim 4, wherein the secondary cell is used for downlinktransmissions only.
 6. The method of claim 1, wherein the second cell isa cell that supports uplink transmissions.
 7. The method of claim 1,wherein the beam index report is provided based at least in part on abeam index report request that is received from the second cell, whereinthe beam index report request is received after the beam failureindication is provided.
 8. The method of claim 7, wherein the beam indexreport request is a normal uplink grant scrambled with cell radionetwork temporary identifier (C-RNTI) or a modulation and coding schemecell radio network temporary identifier (MCS-C-RNTI).
 9. The method ofclaim 1, wherein the beam index report is carried in a medium accesscontrol control element (MAC-CE) dedicated to secondary cell beamfailure recovery.
 10. The method of claim 1, wherein confirmation ofreception of the beam index report is a normal uplink grant scheduling atransmission for a same hybrid automatic repeat request (HARQ) processas a physical uplink shared channel (PUSCH) carrying the beam indexreport.
 11. The method of claim 1, wherein the beam index report isautomatically provided based at least in part on a reporting delay,wherein the reporting delay identifies an amount of time after providingthe beam failure indication, that the UE is to wait before automaticallyproviding the beam index report.
 12. The method of claim 1, wherein thebeam index report is provided in a same communication as the beamfailure indication.
 13. The method of claim 1, wherein the recovery ofthe secondary cell is based at least in part on a dynamic random accesschannel (RACH) procedure associated with beam pairing between thesecondary cell and the UE.
 14. The method of claim 1, wherein therecovery of the secondary cell is based at least in part on a downlinkcontrol information (DCI) beam update associated with the secondarycell.
 15. The method of claim 1, wherein the recovery of the secondarycell is based at least in part on a media access control (MAC) controlelement beam update associated with the secondary cell.
 16. The methodof claim 1, wherein a manner in which the beam failure indication isprovided is determined based at least in part on the beam beingassociated with ultra-reliable low-latency traffic.
 17. The method ofclaim 1, further comprising: providing a secondary cell index associatedwith the secondary cell in the beam index report.
 18. A user equipment(UE) for wireless communication, comprising: a memory; and one or moreprocessors operatively coupled to the memory, the memory and the one ormore processors configured to: provide, to a first cell, a beam failureindication associated with a beam of a secondary cell, wherein the beamfailure indication is provided via a dedicated physical uplink controlchannel (PUCCH) resource; and provide, based at least in part onproviding the beam failure indication, a beam index report to a secondcell, wherein the beam index report is to cause recovery of thesecondary cell to be triggered, and wherein the beam index reportincludes information that identifies a preferred beam associated withthe recovery of the secondary cell.
 19. The UE of claim 18, wherein thebeam is associated with ultra-reliable low-latency traffic.
 20. The UEof claim 18, wherein the beam index report is provided based at least inpart on a beam index report request that is received from the secondcell, wherein the beam index report request is received after the beamfailure indication is provided.
 21. The UE of claim 18, wherein the beamindex report is automatically provided based at least in part on areporting delay, wherein the reporting delay identifies an amount oftime after providing the beam failure indication, that the UE is to waitbefore automatically providing the beam index report.
 22. The UE ofclaim 18, wherein the beam index report is provided in a samecommunication as the beam failure indication.
 23. The UE of claim 18,wherein the recovery of the secondary cell is based at least in part ona dynamic random access channel (RACH) procedure associated with beampairing between the secondary cell and the UE.
 24. The UE of claim 18,wherein the recovery of the secondary cell is based at least in part ona downlink control information (DCI) beam update associated with thesecondary cell.
 25. The UE of claim 18, wherein the recovery of thesecondary cell is based at least in part on a media access control (MAC)control element beam update associated with the secondary cell.
 26. TheUE of claim 18, wherein a manner in which the beam failure indication isprovided is determined based at least in part on the beam beingassociated with ultra-reliable low-latency traffic.
 27. The UE of claim18, wherein the one or more processors are further configured to:providing a secondary cell index associated with the secondary cell inthe beam index report.
 28. A non-transitory computer-readable mediumstoring one or more instructions for wireless communication, the one ormore instructions comprising: one or more instructions that, whenexecuted by one or more processors of a user equipment (UE), cause theone or more processors to: provide, to a first cell, a beam failureindication associated with a beam of a secondary cell, wherein the beamfailure indication is provided via a dedicated physical uplink controlchannel (PUCCH) resource; and provide, based at least in part onproviding the beam failure indication, a beam index report to a secondcell, wherein the beam index report is to cause recovery of thesecondary cell to be triggered, and wherein the beam index reportincludes information that identifies a preferred beam associated withthe recovery of the secondary cell.
 29. The non-transitorycomputer-readable medium of claim 18, wherein the beam is associatedwith ultra-reliable low-latency traffic.
 30. An apparatus for wirelesscommunication, comprising: means for providing, to a first cell, a beamfailure indication associated with a beam of a secondary cell, whereinthe beam failure indication is provided via a dedicated physical uplinkcontrol channel (PUCCH) resource; and means for providing, based atleast in part on providing the beam failure indication, a beam indexreport to a second cell, wherein the beam index report is to causerecovery of the secondary cell to be triggered, and wherein the beamindex report includes information that identifies a preferred beamassociated with the recovery of the secondary cell.